code: def __exit__(self, exc_type, exc_val, exc_tb):
      for key in self._env_keys_added.keys():
          os.unsetenv(key)
  
imports: import dataclasses
  import os
  import pytest
  import yaml
  from jina import Deployment, Flow, requests
  from jina.constants import __default_executor__
  from jina.excepts import BadConfigSource
  from jina.jaml import JAML, JAMLCompatible
  from jina.serve.executors import BaseExecutor
label_desc: Use image node_id 3 for calling the EnvironmentVarCtxtManager obj's underlying member method code with example usage: obj.__exit__(exc_type, exc_val, exc_tb) without return types